PUBLIC-HEALTH IMPACT OF SCHISTOSOMIASIS - DISEASE AND MORTALITY

The public health significance of schistosomiasis is often underestima ted for two reasons. First, like all helminthic infections, the distri bution of worms in any community is widespread but uneven, i.e., few h ave heavy infections and severe disease, while many have lighter infec tions and fewer symptoms. Some people with very few worms may have no symptoms. Secondly, severe disease usually follows after many years of silent or mildly symptomatic infection. Even if only 10% of those 200 million infected with schistosomiasis have severe clinical disease, t his still represents 20 million seriously ill people. Of the remaining 180 million infected people, an estimated 50-60% also have symptoms-a public health problem of enormous proportions. The impact on public h ealth can be assessed in terms of the frequency and severity of schist osomiasis-related disease, incapacity and premature death. This articl e presents extracts from the Expert Committee's recently published sec ond report and deals with morbidity and mortality, as well as the link s between schistosomiasis and cancer, nutrition and intercurrent infec tions, and the immune response to schistosomiasis.